Scraping apparatus for pelletizing pan



Feb. 16, 1965 R. c. MCDOWELL ETAL 3,169,269

SCRAPING APPARATUS FOR PELLEfI'IZING PAN Filed Aug. 6, 1962 8Sheets-Sheet 1 1 VENTOR5. Passer M: DOWELL BY THoMAs E. BAN

ATTORNEY.

Feb. 16, 1965 R. c. MCDOWELL ETAL 3,169,269

SCRAPING APPARATUS FOR PELLETIZING PAN Filed Aug. 6, 1962 8 Sheets-Sheet3 FLE EI INVENTORfi 205521 C Me DOM/ELL BY THOMAS E. BAN

r ATTORNEY Feb. 16, 1965 R. c. MCDOWELL ETAL 3,169,259

SCRAPING APPARATUS FOR PELLETIZING PAN Filed Aug. 6, 1962 8 Sheets-Sheet4 mvrsmoxs. Ro/aeer C. M: DOWELL BY Taomns E. BAN

ATTOENEK 1965 R. c. MCDOWELL ETAL 3,159,259

SCRAPING APPARATUS FOR PELLE'I'IZING PAN Filed Aug. 6, 1962 8Sheets-Sheet 5 5g 57 4b 55 ga /1011111 48 54 5/ f INVENTORS. Po/aEe-r C.Mc POWELL BY THOMAS E. BAN

QTTO ENEY.

Feb. 16, 1965 R. c. MQDOWELL ETAL 3,169,269

SCRAPING APPARATUS FOR PEILLETIZING PAN 8 Sheets-Sheet 6 Filed Aug. 6,1962 IVV TOR5. ROBE/2r Cf MCDOWELL BY THO/W42 5. 541v ATTORNEY.

Feb. 16, 1965 R. c. MCDOWELL ETAL 3,169,269

SCRAPING APPARATUS FOR PBLLETIZING PAN Filed Aug. 6, 1962 a Sheets-Sheet7 mvmv'rons. Q0/3527 C Mc Paws/.1.

W ii? i ATTORNEY 1 United States Patent Ofilice 3,169,259 Patented Feb.16, 1965 3,1551%? RATES PELLETEZENG veil, illeveland, Thomas E. Frau,

" by niesne assign- This invention relates, as indicated, to apparatusfor pelletizin or agglomerating materials, or the preparation of nodularmixtures, and especially apparatus for pelletizing pulverized iron orecompositions. More particularly, the invention relates to improvedapparatus for preventing undue accretion of material on the operatingsurfaces of pelletizins apparatus. Vhile this invention is applicable topellet or nodule forming, and mixing apparatus of the rotary drum or pantypes, it will be illustrated in reference to pellctizing pans of thetypes in use for forming pellets of various iron ore containiriscompositions, especially moistened ore aggregates.

Felletizing devices depending upon a rotating inclined conical,cylindrical, or combined conical-cylindrical section and especiallythose, the inner surface of which is characterized by a plurality offlights radially and axially disposed at successively increasingdistances from the base of the vessel, are old. l-leretofore, accretionof the mateial on the side wall or rim surface of the vessel has beencontrolled by means of a stationary scraper adapted to conform in itsprofile to the profile of this portion of the vessel. Accretion ofmaterial on the bottom surface or" the pelletizing device has beencontrolled in the past by rotating means, numerous examples of which areknown to those skilled in the art.

A principal problem scrap with the stationary side wall c apparatus hasbeen that from time to time, of the paste mixture would be broken off bythe scraper and fall to the pelletizing portion of the apparatus withthe resultant formation of greatly oversized pellets which must beseparated from those of the desired size. A substantial portion of thmaterial charged to the 'elietizing vessel, then, would requireseparation and possibly re-working in order to avoid unnecessary loss ofmaterial. The removal of such chunks of material by a gouging action ofthe stationary scraper would also destroy the carefully built up surfacecoating of the material being called or pell tized with resultantimpairment of er ficiency.

The present invention now provides a scraping apparatus which coactswith the surface or rim of the pelletizing apparatus to control the eat.it of accretion of material on the surface, and at the same time avoidthe formation of large conglomerates of such material and the attendantformation of improperly sized pellets. Essentially, the accretioncontrolling apparatus of the present invention is characterized byhaving a rotatable shaft disposed in spaced relation to the rim surfaceand a plurality of material engagiri members disposed in axially spacedand outwardly projecting relation along said shaft for rotationtherewith, the length or" the projecting members at progressivelylongitudinal positions on the shaft being adapted to conform with theprofile of the pelletizing surface.

In a preferred embodiment, the projecting material engaging memberscomprise a plurality of projecting fingers radially protruding from therotatable shaft at 90 intervals and at progressive longitudinalpositions on the rotating sh The ex ent of projection of the respectivefingers from sequentially axially disposed right angularly relatedpositions forms at the combined outer extremities a profile whichconforms with the profile of the pelletizing rimmed surface. Thedisplacement of the profile cut by the material engaging members fromthe substrate surface of the pelletizing pan is adjustable. Inoperation, the individual scraping fingers contacting the coated surfacecause the surface to become roughened or fractionized for improvedmixing and pelletizing over the relatively smoother surface resultingwhen stationary scrapers are used and are operating properly.

The profile maintained by the scraping apparatus hereof may be rightcylindrical, conical, spherical, stepped, or any combination of these.For illustrative purposes, a profile of a flaring or conical side wallhaving a plurality of steps or troughs disposed on the inner surfacethereof will be used, it being understood that the present apparatus isadaptable to provide any desired profile.

Other objects of the invention will appear as the de scription proceeds.

Through the accomplishment of the foregoing and related ends, saidinvention, then, consists of the means hereinafter fully described andparticularly pointed out in the appended claims, the followingdescription setting forth in detail certain illustrative embodiments ofthe invention, such disclosed means constituting, however, but a few ofthe various forms in which the principle of this invention may beemployed.

Briefly stated, then, the present invention comprises in combination amixing or pelletizing apparatus having a material receiving vesselmounted for rotation on an inciined axis, said vessel having a base anda side wall extending therefrom, and a mechanism coacting therewith tocomminute and maintain a predetermined level of charged material alongthe side wall including a frame overlyin the vessel, and a shaftrotatably journalled in the frame witits axis disposed in spacedrelation to the side wall of the vessel. A plurality of materialengaging members are disposed in axially spaced and outwardly projectingrelation along the shaft for rotation therewith, the axial length of theprojecting members along the shaft being adapted to conform with theprofile of the side wall surface. Means are also provided for rotatingthe shaft in conjunction with the rotation of the vessel.

in the annexed drawings:

FIG. 1 is a partially cut-away side elevation of a pelletizing apparatusand showing side and bottom surface scraping units;

FIG. 2 is a front elevation of the apparatus shown in F1. 1;

FIG. 3 is a rear view of the apparatus of FIG. 1 showing drive motorarid scraper unit supporting framework;

FIG. 4 is a side elevation of the pan rim or vessel rim scraping unit onenlarged scale;

FIG. 5 is a bottom elevation of the rim scraping unit shown in FIG. 4;

FIGS. 6 and 7 are detailed side and top elevations, respectively, on anenlarged scale of a rotatable bar for supporting a plurality of scrapingfingers for the rim scraping unit;

FIG. 8 is a cross-sectional view taken on the plane indicated by theline 3-8 of FIG. 7 showing a preferred mode attachment of the scrapingfingers;

FIG. 9 is an end view of the scraping finger attachment assembly shownin FIG. 8;

FIGS. 10 and ll are elevations of scraping fingers;

FIG. 12 is a side elevation on an enlarged scale of a pan bottomscraping unit and supporting frame;

FIG. 13 is an elevation of the bottom scraper supporting frame shown inFIG. 12;

FIG. 14 is a cross-sectional view in the plane indicated by the line14-14 of FIG. 12; and

FIG. 15 is a bottom elevation of a rotatable bar for supporting aplurality of scraping fingers for the bottom scraping unit.

Referring nowmore particularly to FIGS. 1, 2 and 3, there is here showna pelletizing apparatus of the rotating disk type having a materialreceiving vessel it) mounted for rotation on an inclined axis. Becauseof the size to which devices illustrative of the present invention maybe constructed, e.g. 18 feet in diameter, the construction of the pan orpelletizing vessel 19 is conveniently of the double wall type such asshown in FIG. 1; Driving means 11, including suitable motor 12 and gearreduction means 13, are mounted on a suitable frame 14. 14 is adapted tovary the angle of inclination of the motor and gear reducing elementsand is accordin ly conveniently adjustable to a number of predeterminedpositions. In the apparatus shown in FIGS. 1-3, legs 15 which areparts'of frame 14 are rotatably anchored in anchor 16 by 7 means of pin17. V

The opposite extremity of leg 15 is perforated and coacts withperforatedsupport 13 through a pin 19 to adjust and secure the angle ofinclination of the axis of pan 10, support 18 being provided with aplurality of pin receiving holes 29 to enable such adjustment. Thesupport and drive means for the pelletizing apparatus form no part ofthe present invention. 7 i

The inner surface of the pan 10 is composed of a bottom or base 21 and aflaring side wall or rim 22. As shown in FIG. 2, there is convenientlyprovided in overlying relationship with the rim and bottom surfaces, anexpanded metal liner 23 covering in surface-contour conforming adjacentrelationship therewith. The function of-such liner is to aid theformation and retention of a relatively thick coating ofpelletizablematerial on the bottom and rim surfaces of the pan to. Other means forcausing adhesion of a layer of material being pelletized, or othercompatible material, e.g. bentonite, to'th'e operative surfaces of thepelletizing pan or vessel may, of course, be employed.

A In the embodiment shown in FIGS. 1-3, the flaring side Wall 22 isdesirably provided with a plurality of annular surfaces, such as annularsurfaces 2-4, 2-5 and 26, disposed in planes which are parallel to'thebase of the vessel at successively increasing distances from the basealong said side wall 22. Each annular surface 24, 25 and 26 is providedwith an axially directed depending portion or flange 27, 28 and 29,respectively. Flanges 27, 28 and 29 all intersect the outwardly flaringside wall 22, and as shown in FIG. 1 are preferably in spaced rela-Frame ing the uniformity of action of the scraping fingers on thesurfaces controlled thereby.

The exact form of the scraper supporting mechanism or frame is notcritical, and indeed, in some instances, it

'may be desirable to suspend the frame for supporting the scrapers froma structure independent of the pelletizing apparatus itself. However,for ease of installation and stabilit with resnect to motions to whichthe pelletizing pan itself may be submitted, the structure which isshown in-FlGS. 1??) is preferred.

FIGS. 4-9, inclusive, illustrate details on an enlarged scale, of .apreferred form of rim scraping apparatus in accordance with the presentinvention. FIGS. it) and 11 are elevations of material engaging fingerstypical of those used. in the scraping apparatus hereof. scrapingapparatus 37 includes a shaft 4% journalled for rotation, and preferablysupported in a cradle carried by the frame bars 34 and (FIG. 2). Cradleor channel 41 is generally of box-like construction having end walls 52and 43, respectively, and having mounted. thereon bearings 44 and 45 inwhich the shaft 445 is journalled for rotation.

Upstanding side walls 5% and on of cradle 41 coact with the bottom 61 toprovide a collector or guard for the material centriiugally dischargedfrom the fingers. Means may be provided, if desired, for returning suchmaterial to the pan for re-working, e.g. vibratory means.

' Cradle supporting leg 64 is secured to the bottom 61 and tion from thenext annular surface, i.e. exposing side wall portions 30, 31, 32 and33, respectively. The combination, then, of the annular surface, e.g.annular surface 24,

with flange portion, for example, flange 28 and, where present, sidewall portion 31, form a trough in which the pelletizing operation or aportion thereof occurs. In the apparatus shown in FIG. 1, for example,-aseries of four such pelletizing troughs are provided at successivelyincreasing radial and axial distances from the base 21.

In FIGpl rim scraping apparatus, generally indicated at 36, and bottomscraping apparatus, generally indicated ferred structure.

Frame 39, as shown best in FIG. 2, includes a pair of parallel,horizontally disposed bars; namely, upper bar 34 and lower bar 35.disposed in overlying relationship across the open, or materialreceiving mouth of the pan 1t). Suitable compression and tension bracingmembers 36a,

37a, 38, 39a are conveniently provided to improve the rigidity of thescraper supportingv frame, thereby improvextends laterally therefrom forengagement with frame bar 35. Jack screw as coacting between the leg 64and the bar 35 enables adjustment of the spacing between the distalfingers id and the rim or side wall 22. Spacing of a the proximalfingers, i.e. those near the drive motor 46,

from the side Wall 22 is accomplished by interposing shims 66 betweenthe bottom 61' of cradle 41 and frame bar 34.

Shaft 46, as shown in FIG. 8, is preferably of square cross section,such as formed by welding together the free marginal edges of a pair ofright angle iron members. Shaft 44) has a length which is sufiicient tospan the width of the flaring portion or rim portion 22 of thepelletizing apparatus, when disposed parallel to and in a plane normalto the surface.

As indicated above, shaft at is provided at its opposite ends withjournals 62 and 63 which are mounted in bearings 44 and 45 secured tothe end walls 42 and 43 of the cradle 41, and which in turn is supportedby overlying frame bars 34 and 35, respectively. Motor 46 is connectedthrough suitable gear reduction and clutch means, generally indicated at47, to impart rotatory motion to the shaft 4th It should be noted at'this point that in the preferredembodiment, the direction of rotation ofthe scraping fingers is counter to that of the pelletizing bowl. Thus,where the pelletizing bowl It) is rotating in a clockwise direction, asshown in FIG. 2, the direction of rotation of the scraping device willbe counter-clockwise. Speed of rotation of the rim scraper isconveniently from about 60 to about r.p.m., whereas the speed ofrotation of an 18 foot diameter bowl is about 6-12. r.p.m.

' The scraper is characterized by a plurality of radially extendingmaterial engaging fingers or bars 48 secured to the shaft 40 forrotation therewith. The fingers 48 are so positioned and disposed alongshaft to, and are provided with such diverse lengths of radialprojection from shaft 4% thatwhenthe shaft 40 is rotated, the outerextremities of the projecting fingers 43 .trace a profile whichcorresponds to the profile of the flaring rim portion or side wall 22.As shown in FIGS. 10 and II, which are typical examples of materialengaging fingers 48, these are conveniently cylindrical bars threaded atone extremity 49 for adjustable retention in rotor 4-0. The oppositeextremity 50 is contoured to correspond to the contour of the side wallportion 22. The length of the finger 48 will, of course, vary with theThe rim;

displacement of the side wall surface from the center line of rotor at}which, as indicated above, is disposed parallel to the side wall 22.Bars 43 are conveniently made from tool steel heat treated to harden thesteel. The degree of hardness will depend on the abrasiveness of thematerial contacted by the fingers. For some purposes, it is desirable toprovide the fingers with high rake and relief angles in such manner thatthey are essentially self sharpening. to reinforce the material engagingtips with very hard tool steel.

FlGS. 6 to 8, then, show in greater detail the structure of rotor andthe position of the holes 51 and tapped holes 54 for retaining thefingers 43. Thus, there are provided, for example on one surface, forexample the surface shown in FIG. 6, holes 51 in staggered relation toeach other progressively in an axial direction. The hole 51 extendsthrough the parallel opposed surfaces 52 and 53 (FIG. 8), for example,each finger passing completely through the rotor 43 for more rigidsupport thereof. Thus, the opening provided in surface 52 is a drilledhole 51, and its coacting bore in the opposite surface 53 is a tappedhole 54 for threaded engagement with the threaded portion 49 of amaterial engaging finger 48. FIG. 8 is a typical section through allholes in the rotor 45 In order to lock the fingers it; into position,there may be provided, as shown in FIG. 8, a clevis 55 welded to akeying bar 56 which is adapted to be received in a small bore 57 in theface of shaft and adjacent each threaded hole 5d. The side arms of theclevis 55 are adapted to receive a cotter pin 53 which extends throughthe bar 43 and prevents rotation thereof, which rotation would result inchanging the lateral projecting distance of the finger 48 from the rotoror shaft so. The fingers 48 undergo wear during operation and byremoving the cotter pin 58, it then becomes possible to adjust thelateral projecting distance of the fingers 43 as may be required.

in the preferred embodiment shown in the drawings, the disposition ofthe scraping fingers 48 is such that successive fingers d3 axially ofthe shaft 4% are at right angle to each other, and a line passingthrough the center lines of each successive finger, a fixed distancefrom the axis of shaft 4d and toward the scraping end of the fingerdescribes a helix surrounding the shaft 40. Dependins on the size andconfiguration of the pelletizing pan, the successive fingers 48 may bearangular relations to each other different from 90, which is preferred,en. 45, 60, 120, 180. The width and terminal configuration of eachfinger is such that the profile traced during rotation by the series offingers is continuous at the pelletizing surface of the rim and followsthe con tour thereof.

When rotated by motor 46, the fingers successively engage the materialbuilding up on the surface and rasp or comminute it to form smallerparticles which are returned for reworking. The rim scraping apparatusis preferably located at the 12:09 oclock position at which point itwill not interfere with the normal pel etizing operation. The latteroccurs chiefly in the region of the lower left hand quadrant forclockwise rotation of the pan, and in the lower right hand quadrant forcounterclockwise rotation. Thus, in either case, the rim scraper islocated beyond the point in the vessel where pelletizing is occurring.This point, or angular disposition, will vary with the amount ofinclination of the pan axis.

Undesirable build-up of material on the bottom of the pan is preventedby separate scraping apparatus, and FIGS. 12 to show details of a bottomscraping apparatns which coacts with the rim scraping apparatus tomaintain a predetermined thickness of material on the pelletizing pansurface. There is shown a bottom scraper supporting frame 73 adapted tobe supported also on upper bar 34 and lower bar and anchored thereto byany It may also be found desirable suitable means, e.g. U-bolts '71 and'72. Motor 73 mounted on support frame 7% is coupled through anysuitable gear reduction device 74 to shaft 75. Shaft '75 is mount ed forrotation in pillow blocks 76 and 77 also carried by frame 7%, and in aplane normal to the bottom 2f of the pelletizing pan.

Shaft 75 has secured to its free end, as for example by key 75a, ascraper bar holder arm '73 for rotation therewith in a plane parallel tothe bottom 21. The point of attachment of the shaft '75 to the arm 78 isdesirably such that the radial portions of the arm '78 are of differentlengths to provide maximum surface coverage as a result of the combinedrotation of the pelletizing pan and the scraper arm. In the structureshown in FIGS. 12 and 15, portion 79 is one half as long as portion 36.

Scraper bar holder arm 78 is provided at each of its ends with aplurality of clamps, e.g. clamps $1, 32, 83 and 84, adapted to receiveand retain scraper bars, e.g. bars 35, 85, 87 and 88, respectively. Bars35, 86, 87 and 38 are conveniently tool steel bars of rectangularcrosssection heat treated to provide a hard surface.

In the preferred embodiment shown in the drawings, the bottom scrapingapparatus is mounted and the holder arm 73 proportioned so that thecircle described by the :ajor arm portion 39 passes over the center ofthe pelletizing pan bottom 21 and over the circumference of the bottom21. The speed of rotation is desirably from about 60 to 90 rpm. as withthe rim scraper when operating in an 18 foot diameter bowl revolving at6 to 12 rpm.

In operation, a mixture of iron ore with water (12% 1-1 0 approximately)is charged to the pelletizing pan, for example by a belt conveyor. Therotation of the pan causes the moist material to roll over the roughbottom and rim surfaces. initially, the action is to prepare atractionized and pan protecting surface of damp ore mixture coating theentire pan surface including the bottom and rim surfaces. Pellets areformed in the usual manner, but the build-up of material on the surfacescontinues. At a predetermined level of build-up, cg. 1" from the pansurface, the scrapers become effective in removing any further accretionof pelletizing material and providing a roughened or tractionizedsurface. With the rim scraper device of the parent invention, no largechunks of slurry are formed which result in greatly oversized pelletsand uniformity of the pelletized product is improved thereby. The bottomscraping apparatus coacts with the rim scraper to maintain a uniformlayer of material adhering to the entire pan surface.

Other modes of applying the principle of this invention may be employedinstead of those specifically set forth above, changes being made asregards the details herein disclosed provided the elements set forth inany of the following claims, or the equivalent of such be employed.

It is, therefore, particularly pointed out and distinctly claimed as theinvention:

1. In combination, a material receiving vessel mounted for rotation onan inclined axis, said vessel having a base and a side wall extendingtherefrom, and a scraping mechanism coacting therewith to maintain apredetermined thickness of charged material on the side wall beyond apredetermined angular disposition of said vessel, including a framedisposed in spaced overlying relation beyond said predetermined angulardisposition of said vessel, a shaft rotatably journalled in said frameand having its axis disposed in overlying spaced relation to the sidewall of said vessel, a plurality of material engaging members disposedin axially spaced, outwardly projecting relation along said shaft forrotation therewith, said members having individual lengths adapted toconform to the profile of said side wall of said vessel, and means forrotating said shaft.

2. In combination, a material receiving vessel mounted.

sively increasing radial and axial on the side wall of said vessel, andmeans for rotating saidshaft.

3 In combination, a material receiving vessel'mounted for rotation on aninclined axis, said vessel having a base on an outwardly flaring sidewall having 'a plu-' rality of annular surfaces disposed in planesparallel to the base of said vessel at successively increasing distancesfrom the base along said side wall, each annular surface having anaxially dependent portion intersecting the outwardly flaring side Wallin spaced relation from the next annular surface to form a plurality ofpelletizing troughs at successively increasing radial and axialdistances from said base, a scraping mechanism coacting therewith tomaintain a predetermined thickness of charged material on the side wall,including 'a frame disposed in spaced relation overlying the vessel, ashaft rotatably journalled in said frame With its axis disposed inspaced parallel relation to the outwardly flaringside wall of thevessel, a plurality of material engagingmembers disposed in axiallyspaced and outwardly projecting relation, along said shaft, for rotationtherewith, said members varying in length to conform to the profile ofdistances from said base, and a scraping mechanism coacting therewith tomaintain r 8 1 the plurality of troughs formed on the side wall of saidvessel, and means for rotating said shaft.

4. The combination of claim 3 in which successive material engagingmembers are disposed at right angles to each other.

5. The combination of claim 3 in which each of said material engagingmembers is a cylindrical bar including means coacting with said shaftfor securing the memher in fixed relation with said shaftt 6. Thecombination of claim 3 in which said shaft is a tubular member ofrectangular cross-section.

, 17. The combination of claim 6 in which each material engaging memberis a cylindrical bar traversing both parallel opposed surfaces of saidrectangular shaft.

8. The combination of claim 7 in which coaxial barreceiving holes areprovided in each face for each said bar, at least one of which isadapted for threaded engagement with said bar. 1

9; The combination of claim 8 including releasable means for preventingrotation of each said bar.

10. The combination of claim 9 in which the bars are so disposed aboutsaid shaft that a line passing through the center line of eachsuccessive bar a given distance toward the material engaging extremitythereof describes a helical form about said shaft. 1

References @ited hy the Examiner UNITED STATES PATENTS WILLIAM J.STEPHENSON, Primary Examiner.

1. IN COMBINATION, A MATERIAL RECEIVING VESSEL MOUNTED FOR ROTATION ONAN INCLINED AXIS, SAID VESSEL HAVING A BASE AND A SIDE WALL EXTENDINGTHEREFROM, AND A SCRAPING MECHANISM COACTING THEREWITH TO MAINTAIN APREDETERMINED THICKNESS OF CHARGED MATERIAL ON THE SIDE WALL BEYOND APREDETERMINED ANGULAR DISPOSITION OF SAID VESSEL, INCLUDING A FRAMEDISPOSED IN SPACED OVELYING RELATION BEYOND SAID PREDETERMINED ANGULARDISPOSITION OF SAID VESSEL, A SHAFT ROTATABLY JOURNALLED IN SAID FRAMEAND HAVING ITS AXIS DISPOSED IN OVERLYING SPACED RELATION TO THE SIDEWALL OF SAID VESSEL, A PLURALITY OF MATERIAL ENGAGING MEMBERS DISPOSEDIN AXIALLY SPACED, OUTWARDLY PROJECTING RELATION ALONG SAID SHAFT FORROTATION THEREWITH, SAID MEMBERS HAVING INDIVIDUAL LENGTHS ADAPTED TOCONFORM TO THE PROFILE